High Reliability, Modular Radiotherapy Treatment Linac for cancer care in Developing Countries

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Currently Africa has less than 10% of the required capacity to deliver radiotherapy to cancer patients. The participants in this project are working with UK and global collaborators, such as CERN and the International Cancer Expert Corps (ICEC), to develop medical linac solutions in challenging environments in Africa. The key factors to address are the lifetime, service and repair of components in the linac of the radiotherapy system. This project aims to address these factors by making changes to the design in addition to implement the modular design approach.During a previous project we investigated the use of RF pulse modulated gridded guns to inject bunches of electron beams into the RF structure to increase capture. The results of the project demonstrated that it's possible to provide almost 100% capture and deliver the beam with a very narrow energy spread (typical radiotherapy systems are only able to capture 50% of the beam). However recent studies have suggested the use of the grid reduces the cathode lifetime by a factor of three. The studies also demonstrated that the linac efficiency can be improved by operating first cell of linac at lower gradient enabling 90% capture, with only 25% of electrons in the low energy tail using convenient DC pulse modulated guns. We believe that this effect is due to velocity bunching and request funds to further study this to attempt to reach 100% capture with no electrons in the tail. Such an approach could allow very long lifetimes with little maintenance. Modular design will improve the capability to repair when the system does fail.